<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        // let a="zyh"
        // console.log(a);
        // a=100
        // a+=10
        // console.log(a);

        // let a=10;
        // console.log(typeof a);
        // let b="aaa"
        // console.log(typeof b);
        // let c=true;
        // console.log(typeof c)
        // let d;
        // console.log(typeof d);
        // let e=[]
        // console.log(typeof e);
        // let f={}
        // console.log(typeof f);
        // let g=null
        // console.log(typeof g);

        //运算符
        // console.log(10>"1");
        // console.log(10=="10");
        // console.log(10==="10");

        // let arr1=new Array();
        let arr1 = [1, 2, 3, "hello", true]
        console.log(arr1.length);
        // 增
        arr1[5] = 1;
        console.log(arr1);
        // 删
        arr1.splice(5, 1);
        console.log(arr1);
        // 改
        arr1[0] = 2;
        console.log(arr1);
        // 查
        console.log(arr1[3]);
        console.log(arr1[20]);
        arr1[100]=100;
        console.log(arr1[90]);
        arr1["hello"]=2;
        arr1[-1]=3;
        console.log(arr1);
        console.log(arr1.length);
        
        
        



    </script>
</body>

</html>